Rollover CAE Analysis And Lightweight Design For School Bus Body

Safety, energy saving and environmental protection are the major topics fortoday’s automobile.For the time being, automotive crashworthiness and light-weighting design combination is the main effective means of energy-saving emissionreduction at present. As a special bus，the school bus is an important means oftransportation in the city and township highway. There is very wide market prospectin China，so the safety and lightweight research on school bus will have veryimportant practical value.This paper takes a schoolbus as the research object，using CATIA to establish3Dmodel. And analysises the stiffness and modal of school bus body by using finiteelement method，gets the deformation of bending and torsion conditions and the dataof free modal，in addition，does the strength analysis of acceleration，braking andturing，makes sure that the stiffness and strength of body structure meet designrequirements. Obtain the first-order modal frequency12.98Hz, and the-sixth ordermodal frequency28.09Hz, between the road excitation（3Hz） and engine excitation（35Hz），verify the rationality of the bus body design.Uses HyperWorks and LS-DYNA to analysis rollover collision safety on the busbody, study the collision safety of body structure. For the poor crashworthinessproblem, has a reasonable design of improving the structure, get a new satisfied busbody structure meets ECE-R66requirements.By the use of OptiStruct，has thelightweight study of body frame， combine the sensitivity analysis with sizeoptimization method，optimize the beam cross-section thickness. On the basis of newbody structure，Use orthogonal test method to determine the lightweight components，and replaced their steel material by aluminum alloy and magnesium alloy，so gets thesteel-aluminium-magnesium hybrid lightweight body structure. Then adoptscompromise programming multi-objective morphology optimization design methodto improve its stiffness and modal properties. so as to achieve a lightweight design ofschoolbus body.Verify the performance of steel-aluminium-magnesium hybrid lightweight body structure，compared with orginal frame，the total mass reduced about18.27kg，thefirst-order frequency increased about0.49Hz，although bending and torsional stiffnessdecreased a little,the performance basically met the requirements of design, thelightweight method is feasible. Results of the design proved the lightweight method isfeasible.